There is strong demand of high capacity memories for data storage. To obtain high capacity, each memory shrinks in size and the conventional semi-conductor memory devices are facing their limitation. If organic molecules were used in memory cells instead of that, the memory cells would be made smaller in size, because the devices could be constructed by organic molecules, which are as small as single nanometers in size. As a result, storage density of memory using molecules can be increased. One of the ideas is resistance change memory, that the molecules can change its electric resistance between the low resistance state and the high resistance state by applied electric current. For this purpose, molecules having a function to change its resistance depending on the applied electric field or injected charges are introduced between upper and lower electrodes. A memory cell is realized using such molecules, the voltage is applied between the upper and lower electrodes to change the state and the difference of state can be detected by the electric current. In order to improve the reliability of organic molecular memories manufactured under a small design rule, and in order to achieve a reduction in power consumption, a memory cell is required to operate at a low voltage. Thus, it is desired that a resistance change of a memory cell is realized at a low voltage. However, smaller the memory cell, shorter the distances between the charges in the molecules and the surrounding electrodes. Therefore, the charges are easily escaped or leaked from the molecules due to electron movement between the molecules and the electrodes. As a result, the charge retention time (the data retention time or life) of the organic molecular memory becomes shorter.